Tappet silencer



Jan. 20, 1942. w. HOKSTAD TAPPET S ILENCER Filed May 28, 1940 Ml e/71hr W flo/rafaa'.

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Patented Jan. 20, 1942 TAPPET SILENGER William Hokstad, Souris, Manitoba, Canada, as signor of fifty per cent to Ben Dollar, Winnipeg,

Manitoba, Canada Application May 28, 1940, Serial No. 337,705

1 Claim.

My invention relates to improvements in tappets for operating the intake and exhaust ports of internal combustion engines, an object of this invention being to provide a device of this class which will take up the gap normally existing (in the case of side valve engines) between the stem of the valve and the tappet screw head and (in the case of overhead valves) between the free end of the rocker arm and the valve stem.

A further object of this invention is to provide a device of this class by the use of which the tendency for the adjacent parts to loosen and become mal-adjusted, will be reduced.

A further object of this invention is to provide a device of this class which is of simple construction, inexpensive to manufacture and easy to install.

With the above more important objects in view and such other minor objects as may appear as the specification proceeds, my invention consists essentially in the arrangement and construction of parts all as hereinafter more particularly described, reference being had to the accompanying drawing, in which- Figure 1 is a sectional elevation of my invention.

Figure 2 is a sectional elevation illustrating an alternative embodiment of my invention.

Figure 3 is a perspective detail illustrating the tongue, groove and centrally recessed configuration of the embodiment illustrated in Figure 1.

Figure 4 is a section on the line 4-4 of Figure 2.

Figure 5 is a perspective detail illustrating the cam follower employed in the embodiment illustrated in Figure 2.

Figure 6 is a sectional elevation illustrating the embodiment of Figure 2 in association with an overhead valve internal combustion engine.

In the drawing like characters of reference indicate corresponding parts in the different figures.

It is well-known that noisy tappets are responsible for a substantial percentage of the total of the unwanted noises which develop in automobiles, and it is also well-known that the hammering caused by loose tappets causes maladjustment in the surrounding parts, for instance, the lock nuts which are intended to hold the adjustable tappet screws in place, slack off which often makes for even more noise and affects the performance of the associated motor.

My invention is designed to overcome the foregoing objection and describing first the embodiment illustrated in the accompanying Figures 1 and 3, will be seen to comprise in combination with a conventional adjustable tappet screw I and lock nut 2, a two-part tappet 3, of which one part 4 thereof is provided at the lower end with a tongue 5, while the other part 6 is provided with a recipient groove I. g

The part 6 is provided with the usual flanged lower end 8, which rides the cam 9 and the two parts are positioned for vertical oscillation within the tappet guide I0.

Centrally bored, cylindrical recesses I I and 'I2 are formed in the adjacent ends I3 and I4, to receive a spring I5, and it will therefore be seen that the tongue and groove are each divided to provide for the interposition of this spring.

From the foregoing arrangement it will be seen that the effect of the spring I5 is to maintain the two parts 4 and 6 in spaced relationship while the tappet is riding on the low surface of the cam, thus providing the gap I6, which, however, is taken up during the time the breast ll of the cam bears against the tappet. At this time also the adjacent ends will engage so that the Whole tappet moves upwardly, transmitting its motion to the valve stem I8. It follows that at all times the adjustable tappet screw I will be in engagement with the lower end of the valve stem where hammering normally occurs through the usual intermittent engagement of these two parts.

Proceeding next to describe the embodiment illustrated in the accompanying Figures 2, 4, 5 and 6, it will be seen that my tappet I9 comprises a sleeve 20 constituting one part and a cam follower 2| positioned therein but normally projecting therefrom, by which I refer to the period when the cam follower is riding the low part of the associated cam 22 as contrasted with the breast 23 thereof.

The cam follower 2| is limited to endwise movement within the sleeve 20, by virtue of the stationary pin 22', the ends of which are fixed in diametrically opposed drillings formed to receive it, in the sleeve, this pin extending through a transverse slot 23' formed in the follower.

Behind the follower and within the sleeve is a spring 24, the upper end of which'bears against the blocked upper end 25 of the sleeve and the upper end of the sleeve 20 is formed to the shape which is conventional with overhead tappets, to receive the rod 26. 7

From the foregoing it will be seen that my tappet 20, as it oscillates in the guide 21, is free to rotate with the rod 26 as a unit, as is the case with conventional tappets, and that as the follower 2I rides over the breast 23 of the cam, it

first yields under the resistance of the valve spring 28 so that the spring 24 is compressed, but when the lower edge 29 of the slot 23' bears against the pin 22, the whole tappet is moved together with the associated rod 26, the rocker arm 30 and the valve stem 3| against the resistance of the valve spring 28.

With overhead valve assemblies such as I have illustrated in the accompanying Figure 6, the hammering takes place between the free end 32 of the rocker arm and the valve spring retainer cap 33, and from the foregoing description it will be understood that with the arrangement I have described, the parts 32 and 33 are held in engagement at all times under the expansive force of the spring 24.

It is to be understood that either embodiment of my tappet is suitable for side valve engines or overhead valve engines and it will also be seen that the embodiment of Figure l by virtue of the arrangement described, is capable of unitary rotation within the tappet guide.

Since various modifications can be made in my invention as hereinbefore described and as illustrated in the accompanying drawing, and many apparently widely different embodiments of same made within the scope of the claim without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification and drawing shall be interpreted as illustrative only and not in a limiting sense and I desire only such limitations placed thereon as are specifically expressed in the ac- V companying claim.

What I claim as my invention is:

A two-part tappet for internal combustion engines, one part comprising a sleeve and the other an" endwise movable, transversely slotted cam follower positioned within the sleeve but normally projecting therefrom, a spring within said sleeve behind said follower and a stationary pin extending through said slot and into said sleeve permitting limited endwise movement of said follower -against said spring under an associated cam action. a

WILLIAM HOKSTAD.- 

